Fuel injection pump



March 17, 1942.

R. H. SHEPPARD I FUEL INJECTION PUMP Filed Oct. 6, 1938 vA,Z v

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Patented Mar. 17 1942 UNITED STATES PATENT om CE FUEL nfr at'fr gnrvm Richard H. Sheppard, llanoverrla.

Application October 8, 1938, Serial No. 233,640-

12 Claims.

A particular object of the invention is to provide a pump which may be. assembled and disassembled quickly and easily and in which the parts may be interchanged easily with a minimum expenditure of time; incidentally it is an object of my invention to provide a variable bore cylinder whereby the plungers and cylinders may be. more completely interchangeable and where by more tolerance than usual is permissible in the parts.

Another object is to provide a variable throw cam meehanismfor driving the plungers of such pumps. Still another object is to provide an improved cam rider in novel combination with a variable throw cam. A still further object is to provide a variable throw cam mechanism, in

which the throw may be positively and micro-. metrically varied. Another object is to provide a variable throw cam mechanism for fuel pumps in which the throw varying mechanism as well as all the other parts are sealed from dirt, dust, and liquid or other foreign matter.

An important object is to provide an extremely accurate device for precisely varying the efl'ective stroke of reciprocating pumps and in a manner to increase slightly the acceleration of the plunger as the eilective stroke is increased.

A further important object is to provide pump plunger actuating mechanism which operates the plunger in a manner to avoid dribbling at the end of each fuel delivery stroke whether at idling speed or at full load.

Another object is to provide a pump in which the more vital parts such as the plunger, cylinder, cam and cam rider may be made of metal best suited to their individual functions and with respect to efliciency, long life and similar factors while the more bulky parts such as the cam shaft, casing, etc. may be made of less expensive and more easily worked materials.

In the drawing:

Figure 1 is a bottom plan view, partly in section, of the pump as mounted on an engine.

Figure 2 is a transverse sectional elevation taken on line 2-2 oi Figure 1.

Figure 3 is a view looking into the top of the pump casing.

Figure 4 is a detailed view showing the plunger and spring seat connection.

Figure 5 is a fragmentary sectional view showing' a modified form of cylinder.

Referring to Figure l the pump supporting cover M at one end and a connecting flange It atthe other end for mountingthe pump on a supporting-boss I3 01. an engine not shown. Thecover l2 carries a number oi pump cylinders 23 which are held in place as fby tapered pins 2| extending transversely throughthe cover to thus make up a compact cylinder block assembly. 1 I

The casing I0 is .divided into a. cylinder chainber 24 and a cam chamber 26 which are connected by a number of bores 21 in each ot'which.

reciprocates a 'cam rider 28, these riders being cup-shaped and, each having a rim 30 resting on the margin of itsv bore 21 when the pump plunger 3| is held in no load position by the helical spring 33, surrounding the plunger and lower partof the cylinder. Each spring 33 engages the annular shoulder '35of the cylinder body 20 and at the other end engages the spring seat 36 which is held on the plunger. 3| by means of an open washer 31 which washer engages the reduced portion or groove 38 of the plunger and seats in an annular recess "in the underside of the spring seat 36. The plunger acts as a slide valve for the intake port 39.

As best shown in Figure 2 the cam rider 23 is provided with two cam engaging faces 42 and and preferably do not intersect but rather are separated from each other by a narrow strip forming a ridge or nosedS. The axes t2 and d3 of the cylindrical faces t2 and 53 are on opposite sides of the center line of the cam rider and the curves have a radius preferably of somewhat less length than the minimum radiallength of the cam. In its lowest position the cam rider nose M is just outof contact with the tip of the cam when the cam is in no load position so that strictly speaking the cam rider is really a cam wiper. Th construction of cam and rider as shown permits the-plunger to drop awaywith maximum acceleration as the cam leaves the nose 45 and thus'eliminates dribbling at the end of the delivery stroke. v

The variable throw cam mechanism includes a shaft 43 mounted in the sleeve to rotate.

therewith but being axially shiitable in the sleeve when actuated by means of a lri'iurleti headed control screw 5| projecting throughthe- "of the shaft. The sleeve iillisiournalled in-the Y casing i0 is provided with a main cover or head I2, a controlv bronz bushings 55 and 5 6, which are removably b1 th I held in place in each end oi the casing respecin: in 3&3: 223 i castively by the cover I and thezboss IS. The shaft spring and cylind r int th ir res $13 p u is provided with a numbeinoi radial loneiturider cups 28 and then the block is sexedio iz vdinal slots 58 corresponding with the number of 6 casing by means of screws in is 8 pump plungers, in the present case three, each ready to be attached to the engine pump now slot as having a sloping bottom so on which Should it be necessary to chang slides a cam 52 having a correspondingly sloped the pump cylinders or plungers it i: 3?} one or base 63. As relative axial motion is Produced sary to drive out a, tapered pin 2| necesbetween the sleeve and shaft by turning the con- [0 cylinder body a and secure in 1a remove the trol screw 5| the effective radfial length or throw tuted body. The bores in the c v celghe subsuof each cam is varied; that is th c ms project the pump bodies are preferably oi' grea riceivmg l l l m l l v 1/ 016% am 12 mm mar 2 me am 010/66! web/1w)? pay 5m; Maw l 01 film/t1 Ml A166 92 A68 0 a m 2 saozrl/ 7 1 9 II 4. M 1 240577 1 /1 Isa 114 7 475 I up IF 1/1 m WM a, gfmwqbmfl mums We peas 5; 2 zap/M6 ax sy wagon 1a blag/1m v 2 1702 8' can! 9; pa /11116 a cozzeebauqm z e abeq m6 b/rwb 031/9'61? oz D/MGI? p 2 2121305503? 1 1' n F 8 210171118 poppom u on Aiplafl ape/1 pa 1160022021 p0 open 8' v li/rwb b nmiszz ,m e" bzsasnp was grass emu Z6902 NR WWW 4 II 91757175 y b 2 170A! 7 H 20 a musewnm We amp 9 m p11 was? 0; 201041? M D/m1 7 I I. qq m mg gmgp acpfl zm'lbqf W n I /qw WW 11111111161 1 "W 1 mmmc n pa pps cone: 1 we pps pace 3' ye 2pm 2mm? 0' 11M I 1 162mm; rep] n b ocs u asap my 0; [p9 ave n8 zezbsc- I F 111 1 1 I!" I 0! Dim? :amv 121121111152 pg s'nq pp Asp op axe zcmalispja P1 #1 11 4 1 1 I 117 017 W ass eaeo V I v 3. In a fuel injection pump having a cylinder I with'intake and outlet ports, a spring retracted plunger reciprocable in the cylinder and acting as a slide valve for the intake port, a variable throw crest nosed cam for actuating the plunger, a .cam rider between the cam and plunger, 7

said rider having an incurved substantially cylindrical surface for cooperating with the cam nose .to produce constant acceleration of the plunger at a given cam throw, the axis of the cylindrical surface lying in a plane parallel; to'

the. axis of rotation of the cam at such distance therefrom that the entire cylindrical surface lies in a single half of the working face of the rider whereby the acceleration increases slightly with an increase of the cam throw, and means for varying the cam throw from zero stroke to full stroke. v v

4. The pump of claim 3 in which a second surface is recessed in the cam rider adjacent the first surface to form therewith adiametrical ridge or nose, said surfaces each covering about half the bottom surface of the cam rider.

5. A cam rider for a pump comprising a cylindrical cup having an annular flange to serve as a stop to limit axial movement, the bottom wall. of the cup having therein two parallel concave cylindrical recesses forming between them a diametrical rib.

6. The cam rider of claim 5 in which the ra-' dius of the two cylindrical recesses is the same and the axes are parallel and located on opposite sides of the rider axis.

7. A cam follower adapted to be moved in one direction by a rotating cam and moved in the opposite direction by a resilient means such as a spring; said cam follower having a cam engaging face having therein a concave cylindrical recess positioned to one side of the center of the follower with its axis parallel to the axis of rotation of the cam, whereby th follower may end its stroke abruptly.

8. A cam follower comprising a member having a circular cam engaging face, said face having a diametrical cam engaging ridge and having on one side of. said ridge a cylindrical depliliession, the axis of which is parallel with said ge.

- to-the sleeve, a shaft slidably fitting in the sleeve and having longitudinal slots for receiving the 9. In a fuel injection pump, variable throw cam mechanism for actuating a plunger comprising a shaft having a longitudinalslot therein of which the central plane is radial to the shaft, the bottom of the slot being sloped with respect to the shaft axis, a sleeve' telescoped overthe shaft and having a short slot therein,

a cam seated on said sloping bottom and fitting in the short slot whereby'relative axial movement of the shaft and sleeve causes the cam'to move radially with respect to the shaft, said shaft having a pair-of slots therein normal to and adjacent thelongitudinal slot and sloped" similarly to the sloping bottom, and a pin projecting through the cam into said pair of slots whereby the cam is held on its seat when the shaft is shifted axially with respect to the sleeve and means for producing said relative motion thereby to change the throw of the cam.

10. In a fuel injection pump, a casing having a cam chamber, a compound cam shaft rotatably mounted inthe ends of said chamber and comprising a sleeve having a number of cam openings therein, cams slidably fitting in said openings and having radial movement with respect cams, said slots having sloping bottoms engaging correspondingly shaped seatson the cams, and means to keep the cams on their sloping bottoms during retracting movement of the cams,

said means comprising studs projecting from the sides of the cams into stud slots in the shaft normal to the cam slots and sloped in the same. direction as the bottoms of the cam slots.

11. The device of claim 10 in which the sleeve is also provided with stud receiving-slots normal to the longitudinal cam slots and elongated in the direction of cam travel and communicating with the sloped slots in the shaft whereby permitting the cam studs to be removed from or inserted in the cams.

12. A cam blade for pumps comprising a body I having a rounded nose at the top edge and a sloping bottom at the opposite edge whereby the front and back faces are similar while one side face is longer than the other, and guiding studs extending from the fiat front and back faces, said studs and said bottom being adapted to cooperate with slots for altering the throw of the cam.

RICHARD H. SHEPPARD.- 

